Cardboard Creations From Projected Designs

This project is to show a simple technique for fabricating digital designs
with cardboard using hand tools, not smart tools such as a laser cutter.

As I see it, the dramatic increase in making is attributable to the following:

• Low-cost electronics, resulting in:
  • electronics and hardware projects
  • smart tools such as 3D printers
• Open source philosophy, resulting in:
  • shared code
  • shared designs
• Collaboration among makers, resulting in:
  • online interest groups
  • offline maker spaces

Of these, the one category least likely to be available to most people is smart tools due to their cost. Such a shame because when all the above come together a person can move from no experience to a successful making experience in hours. The barriers to becoming a maker are dramatically lowered. Were it not for the lack of smart tools many more people would benefit from making and this got me thinking,

"Are there ways to mimic the benefits of smart tools using hand tools?"

This project is one exercise in using a technique that replaces laser cutting with inexpensive hand tools. To be clear, the goal of this series is only to achieve an effective approximation of what smart tools can do. If we can then where the cost of smart tools is a barrier, these techniques can provide low-cost options.

In this first example, I project and trace a digital design onto cardboard, cut it out using two simple hand tools, then assemble as I would a laser cut equivalent. This first project is of a simple cardboard chair I designed. The results prove the viability of this approach.

This Instructable is not about creating a design. I happened to design this chair in Corel Draw and the finished result can be seen above. To a great extent this is the same design I'd use with a laser cutter using 0.15" thick cardboard. The only differences are the perpendicular scales in the upper left and lower right corners.

If I intend to approximate cutting with a laser then I need my projected design to be square and to scale. If my projection is not square and to scale then my resulting cuts won't be correct. The project won't assemble properly. Building these two corner scales into the design is a key requirement of this technique as you'll soon appreciate.

With the project design complete and in-hand it's time to project and trace.

Getting Video Projection Right

Video projectors vary but two things are always true:

1. Scale of a projected image can change with distance.
   • The closer the projector to the cardboard screen, the smaller.
   • The farther the projector from the cardboard screen, the larger.
2. Skew of a projected image can change with projection angle.

Adjusting Distance to Scale

You need to adjust scale in order to get the correct size projected. For instance, if your design specifies that the length of a side should be six inches then you need to adjust the projector's distance from the cardboard. By moving the projector closer or farther you shrink or enlarge the image. With each adjustment you need to focus for sharpness then measure. Make adjustments till you get one of the corner scales correct.

Why adjust scale for only one corner? Because unless you're extremely lucky and the projection is completely square, meaning the image has no distortion, you'll need to adjust for skew.

Adjusting Skew to be Square

Most likely when you adjusted the scale above for the correct measurement in one corner, the other corner did not measure correctly. For instance, if the lower right hand corner was the correct 6" then the upper left corner was probably longer or shorter than 6". This is due to the projection not being perfectly perpendicular to the cardboard screen and correcting for this is adjusting for skew so we can get a square projection. After achieving a square projection, adjusted to remove distortion due to being skew, both your scales will measure the same 6".

The way you adjust skew is to tilt the projector up and down, left and right. One direction will make things less square while the other direction will make things more square. Getting the left/right adjustment is relatively easy. All you really need to do is project onto the screen at 90% or "straight on". Getting the up/down adjustment is more difficult and may require slipping sheets of paper under the front or back feet of the projector. If you're lucky then your projector will have a "keystone" adjustment which does the up/down adjustment using a lever.

Iterate Until the Image is Square and to Scale

One thing that you'll quickly notice when making the above adjustments throw each other off. Making the image square can throw off the scale and you'll need adjust. Focusing an image can also throw off scale and you'll need to adjust. Moving the projector to adjust scale can distort a previously square image and you'll need to adjust.

This process is trial and error until you get it right. Iterating until your image is square and to scale isn't difficult, it just takes time. However, getting it right is the key to this technique.

Now, Trace Your Image

You're projecting your digital design onto your cardboard. It's square and to scale. Now it's time to commit that image to your cardboard by tracing the projected lines. Use different colors for different types of lines. In this example I've used black for cuts and red for folds.

When you think you've finished it's best to confirm before disassembling your setup. Turn the projector off and on, each time looking for any untraced line segments. Far better to catch and correct any oversight now.

Now is when you get to see the benefits of this approach.

Hand Tools to Use

The best answer to "Which tools should I use?" would be "The tools you already own that will do the trick." That might simply mean using an Xacto or utility knife to cut. However, since this technique was designed for use by kids in a classroom I'd recommend a Canary Corrugated Cardboard Cutter. It's remarkably effective at cutting cardboard and you'd be hard pressed to have a child cut themselves. For folds I used a pizza cutter to make an impression but I wasn't happy with the results so have ordered two options to use in future builds (1 and 2).

Cut and Assemble

The rest of this is pretty straight forward. If your design was projected properly then the result of your cutting and folding will be the three pieces of cardboard. These readily assemble into a small chair. Once assembled, to keep the seat on the legs I simply applied some hot glue, though any glue would work. That's it!

The purposed of this project was to demonstrate a technique.

Here we made a small chair. We could have been making anything from cardboard, of any size. All we needed was a good digital design which we could project, trace, cut and assemble. No laser cutter required, just the right hand tools.

My hope is to discover and share other techniques. Participating more fully in the maker movement shouldn't require expensive smart tools, at least not to get started. The more we get people started down the road to seeing themselves as makers, the better.

If you have ideas or suggestion then please comment below. Thanks!